This topic describes the offset rules and offset order of Apsara File Storage NAS (NAS) resource plans.
Effective time and offset time
After you purchase a resource plan, it immediately takes effect. The resource plan is used to offset the fees for pay-as-you-go bills during its validity period.
For example, you purchased an Extreme NAS resource plan with a capacity of 1 TiB at 10:30:30 (UTC+8) on August 12, 2021. The resource plan was valid for one month. In this case, the storage usage fee of the billing cycle from 10:00:00 to 11:00:00 was offset at around 14:00:00 (UTC+8) on August 12, 2021. The storage usage fee of each billing cycle was not offset until the system generated the bill for the billing cycle.
Offset order
You can purchase multiple resource plans. Resource plans of the same type are used in the following order:
The resource plans are used based on their expiration dates. Resource plans whose expiration dates are earlier are used first. If the expiration dates of the resource plans are the same, the resource plans are used based on their purchase dates. The resource plans that are purchased earlier are used first.
For example, you purchased three General-purpose NAS resource plans in the China (Hangzhou) region: A, B, and C. The expiration dates of A and B are the same and are later than that of C. A was purchased earlier than B. The resource plans are used to offset fees in the following order: C, A, and B.
If the quotas of the resource plans are used up, you are charged for the excess usage by using the pay-as-you-go billing method.
If you have resource plans, storage capacity units (SCUs), and storage plans within your Alibaba Cloud account, storage usage fees are offset based on the sequence shown in the following figure.
Offset limits
NAS resource plans can be used to offset only the storage usage fees of NAS file systems.
Each type of resource plan can be used to offset the storage usage fees of the file systems that correspond to the resource plan type. The following table describes the billable items and offset factors for each resource plan type.
Resource plan type
Billable item
Description
General-purpose NAS resource plan
The fees of the following billable items are offset for General-purpose NAS file systems:
Storage usage of General-purpose NAS file systems (Capacity, Performance, and Premium)
Storage usage of the IA storage class
General-purpose NAS resource plans are used to offset the storage usage fees of the files that are stored in General-purpose NAS file systems (Capacity, Performance, and Premium). For more information about the offset factors for the storage usage of General-purpose NAS file systems and the IA storage class, see Apsara File Storage NAS Pricing.
Extreme NAS resource plan
Purchased capacity of Extreme NAS file systems
Extreme NAS resource plans are used to offset the fees of the storage capacity that is purchased for Extreme NAS file systems. For more information about the offset factor for the storage capacity of each storage class, see Apsara File Storage NAS Pricing.
Region-specific resource plans can be used to offset resource usage fees only in the selected region.
For example, if you purchase a resource plan for the China (Hangzhou) region, the resource plan can be used to offset resource usage fees only in the China (Hangzhou) region.
If the resource plan expires or the actual resource usage exceeds the quota of the resource plan, the pay-as-you-go billing method is automatically used.